Video quality in beginning is good, but after several minutes running video for some time, the video shows a lot of frame drops, and shows the following log messages:

WARNING: from element /GstPipeline:pipeline0/GstOverlaySink:overlaysink0: A lot of buffers are being dropped.

Additional debug info:

XXX/bld-x11/tmp/work/cortexa9hf-vfp-neon-poky-Linux-gnueabi/gstreamer1.0/1.6.0-r0/gstreamer-1.6.0/libs/gst/base/gstbasesink.c(2846): gst_base_sink_is_too_loate (): /GstPipeline:pipeline0/GstOverlaySink:overlaysink0: There may be timestamping problem, or this computer is too slow.

What exactly version of the Linux kernel do you use? There was the known memory fragmentation issue with the 3.0.35 kernel that caused the similar effects. So, the better way is to always use the latest kernel available.